1. Field
The present invention relates generally to a high-performance cooling device for electronic components, and more particularly to an improved tower-type heat pipe and method for making the heat pipe.
2. Prior Art
As the functions and speeds of computer electronic devices such as central processing units (CPUs) are quickly developed, those electric elements generate lots of heat during routine operation. If not properly removed, such heat can adversely affect the operational stability of computers or those electric components may get destroyed. Solutions must be taken to efficiently remove the heat from those electric components. Typically, a cooling device is mounted on those heat-generating devices to remove the heat.
In order to take more heat out of those electric components in a quick manner, heat pipes are widely used in computer industry recently. A heat pipe is a sealed element in which heat is transferred by evaporation, vapor movement and condensation. When the heat pipe contacts the heat source, working fluid in the evaporator region absorbs heat getting into vapor, and then moves toward condenser region. Then the working fluid in vapor state dissipating heat out returns into liquid again. Finally, the liquid passes back to the evaporator region through the wick in the heat pipe. By repeating this cycle, the heat pipe can take large amounts of heat from the heat source.
A tower-type heat pipe is a heat pipe for being vertically mounted on the heat source which generally is a CPU of a computer. The tower-type heat pipe has a base metal plate and a pipe vertically projecting upwardly from the base plate. The base metal plate is used for contacting with the CPU and the pipe is used as a heat pipe. A conventional method for fabricating the tower-type heat pipe is to integrally forge the plate and the pipe. Such a method has the advantage that the pipe and the base metal plate are seamlessly connected together; thus, no leaking will occur between the pipe and the base. However the cost of this method is too high to be widely acceptable. An alternative conventional method is to form the pipe and the metal plate separately, and then solder the heat pipe and metal plate together. This method includes the follow steps. First, a metal plate and a round container with both open ends are prepared. Second, the container is vertically mounted to the metal plate. Third, a wick formed by sintering copper powders or a mesh is formed on an inner wall of the container. Thereafter a soldering process is done to solder a cover to a top of the container and to solder the container to the metal plate. The container is soldered to the metal plate by applying the solder to an outer wall of the container at a bottom end thereof and a top surface of the metal plate. Then, working fluid is injected into the container, and the container is vacuumed through a tube in the cover. Finally, the tube is sealed. Although this method can reduce the manufacturing cost, it has the disadvantage that when the container is soldered to the metal plate, solder may flow through an interface between the bottom end of the container and the top surface of the metal plate into the container to contaminate the wick formed in the container. This disadvantage causes the tower-type heat pipe made by this method can not have a satisfied yield rate.
To solve the aforesaid drawbacks of the prior art, the present invention proposes a tower-type heat pipe and a method for making the same which have the advantages of low manufacturing cost and high yield rate.